The present invention is directed generally to the construction of optical fibers, and, more particularly, to the formation of an optical fiber having a terminal lens.
Photonic devices often employ optical fibers to guide efficiently and control light passing therebetween or therethrough. More specifically, the optical fibers can transfer light between optical devices, guide light to components in the device, transfer light to other optical fibers, or receive light from components in the device or other optical fibers. Such optical fibers typically have a light-transmitting core surrounded by a light confining cladding. The core and cladding have diameters on the order of 8-150 xcexcm and 100-700 xcexcm, respectively, depending on the type of the fiber (single or multi mode) and fiber material (glass or plastic).
Although light can enter or exit the core of an optical fiber directly, the small size of the core means that precise alignment of the core and the light""s source or destination will be required. One way to comply with optical fibers"" precise alignment requirements is to place a collimating lens near the end of the optical fiber; the lens has optical properties and is positioned such that light which would otherwise not enter the optical fiber core is directed into the center of the optical fiber. That is, the lens guides light into the optical fiber""s core.
One known mounting scheme affixes a microlens to the end of the optical fiber. While this arrangement can comply with optical fiber""s stringent alignment requirements, the procedure for mounting the microlens on the optical fiber itself complicates the manufacturing process; if not done properly, the optical fiber and lens will not be coupled correctly, reducing optical performance. Since the effective coupling of fibers and lenses is required in a wide range of photonic applications, such as detectors/lasers, cross-connect devices, etc., great care will have to be taken when using this technique to join the fiber and lens to insure proper alignment and mounting.
At the present time, coupling of the optical fiber and lens is performed manually. Owing to the close tolerances and precise alignments involved, this presents substantial challenges. Manually mounting the microlens to the optical fiber generally is a slow and expensive procedure, in part because it is done using active alignment of the optical components, and in part because only one microlens and fiber can be joined at a time. Further, constant quality control supervision and checking of every microlens/fiber pair may be required to insure that the resulting products, which are individually fabricated, are of uniform quality and all possess the required optical characteristics.
While it is known to form lenses on optical fibers by dipping the optical fibers into liquid, it is difficult to control precisely the amount of the liquid that is applied to the fiber. Consequently, it is difficult to form consistent-size, precisely dimensioned lenses on optical fibers simply by dipping the fiber ends into liquid.
Thus, there exists a need for a fast, precise and inexpensive system for affixing microlenses to optical fibers.
The present invention is directed to the arrangement and fabrication of an optical fiber assembly having an optical fiber and a microlens joined to the face of the optical fiber, the microlens being made from a pre-dispensed droplet of liquid, which liquid maintains its droplet shape and adheres to the face. The microlens can be shaped to guide light between its surface and the core of the optical fiber.
The optical fiber assembly can be made by applying a pre-dispensed droplet of liquid to the optical fiber, the liquid having properties such that the droplet is stable and holds its shape until contacted by the optical fiber. The liquid is adhered to the optical fiber as a droplet at the optical fiber""s face, and the droplet solidified to form the microlens on the face of the optical fiber. If desired, the shape of the droplet can be changed as it solidifies, for example, by an applied electrical field. Changing the droplet""s shape changes the resulting microlens"" optical properties.